Epidemiologic investigations conducted by the health departments in Nebraska and Iowa have linked the outbreaks in the two states to a particular salad mix, and an independent CDC analysis of those data concurs. Most recently, a traceback investigation conducted by the FDA has identified Taylor Farms de Mexico, S. de R.L. de C.V., as the source of the prepackaged salad mix.

Both the FDA and the CDC report that they will continue to work with federal, state and local partners in the investigation to determine whether this conclusion also applies to the clusters of cyclosporiasis cases in other states, because it is not yet clear whether all of the cases reported nationwide are part of the same outbreak.

According to the FDA, its seven-person traceback team has been tasked with identifying geographic clusters of people who have become ill and tracing the path of food those individuals have eaten back to identify any common source. The agency also said it has specialists working on the outbreak in 10 separate field offices.

"The FDA is following the strongest leads provided by the states and has prioritized the ingredients of the salad mix identified by Iowa and Nebraska for the traceback investigation, but is following other leads as well," the agency reported. "This is labor-intensive and painstaking work, requiring the collection, review and analysis of hundreds and, at times, thousands of invoices and shipping documents."

To date, 41 cases of Cyclospora infection have been confirmed officially in CDC laboratories -- one of them via telediagnosis -- and the agency is encouraging state health labs to confirm additional cases by submitting images showing suspected Cyclospora oocysts to the CDC.

During a July 25 press briefing(www.cdc.gov), CDC Director Thomas Frieden, M.D., noted that physicians and other health care professionals need to be mindful of possible Cyclospora infection and request proper testing for "people who have had diarrhea that hasn't gone away over several days."

"The best way to prevent infection with a parasite is to avoid food or water that may have been contaminated," Frieden said. "Because Cyclospora can stick to some food items, washing produce is helpful, but it doesn't eliminate the risk of infection."